Medical body area network (MBAN) with key-based control of spectrum usage

ABSTRACT

A medical body area network (MBAN) system ( 10 ) comprises network nodes ( 12, 14 ) intercommunicating via short range wireless communication. A primary user database ( 46 ) contains information pertaining to usage of a restricted spectrum by primary users wherein the MBAN systems are secondary users of the restricted spectrum. An electronic key generation engine ( 44 ) comprises a digital processing device configured to generate an electronic key (E-key) ( 50 ) indicative of whether the MBAN system is allowed to use the restricted spectrum based on content of the primary users database. An MBAN application server ( 40 ) is configured to distribute the E-key to the MBAN system. The MBAN system includes a spectrum control sub-module ( 52 ) comprising a digital processor configured to select an operating channel or frequency for the short range wireless communication based at least in part on whether the E-key authorizes the MBAN system to use the restricted spectrum.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application Ser.No. 61/323,495 filed Apr. 13, 2010, which is incorporated herein byreference.

The following relates to the medical monitoring arts, wirelesscommunication arts, and related arts.

A medical body area network (MBAN) replaces the tangle of cablestethering hospital patients to their bedside monitoring units withwireless connections. This provides low-cost wireless patient monitoring(PM) without the inconvenience and safety hazards posed by wiredconnections, which can trip medical personnel or can become detached soas to lose medical data. In the MBAN approach, multiple low cost sensorsare attached at different locations on or around a patient, and thesesensors take readings of patient physiological information such aspatient temperature, pulse, blood glucose level, electrocardiographic(ECG) data, or so forth. The sensors are coordinated by at least oneproximate hub or gateway device to form the MBAN. The hub or gatewaydevice communicates with the sensors using embedded short-range wirelesscommunication radios, for example conforming with an IEEE 802.15.4(Zigbee) short-range wireless communication protocol. Informationcollected by the sensors is transmitted to the hub or gateway devicethrough the short-range wireless communication of the MBAN, thuseliminating the need for cables. The hub or gateway device communicatesthe collected patient data to a central patient monitoring (PM) stationvia a wired or wireless longer-range link for centralized processing,display and storage. The longer-range network may, for example, includewired Ethernet and/or a wireless protocol such as Wi-Fi or someproprietary wireless network protocol. The PM station may, for example,include an electronic patient record database, display devices locatedat a nurse's station or elsewhere in the medical facility, or so forth.

MBAN monitoring acquires patient physiological parameters. Dependingupon the type of parameter and the state of the patient, the acquireddata may range from important (for example, in the case of monitoring ofa healthy patient undergoing a fitness regimen) to life-critical (forexample, in the case of a critically ill patient in an intensive careunit). In general, there is a strict reliability requirement on the MBANwireless links due to the medical content of the data.

As MBAN systems become more common in a hospital or other medicalfacility, spectrum usage increases. This can be accommodated byallocating more spectrum to MBAN applications. However, the allocatedspectrum should be of “high quality” as appropriate for transmission ofimportant medical data. Such spectrum is highly coveted. For example,both MBAN usage and aeronautical mobile telemetry (AMT) desire to usethe 2360-2390 MHz spectrum (hereinafter referred to as the “MBANspectrum). In the United States, it has been proposed to allocate2360-2400 MHz for MBAN on a secondary basis, with AMT being the primaryuser for the 2360-2390 MHz spectrum. In such a scheme, the secondaryMBAN users would be required by government regulation to protect theprimary AMT users in the 2360-2390 MHz spectrum space and to acceptpossible interference from those primary users in that spectrum space.

In order to achieve co-existence between primary users and secondaryusers, some restrictions (or spectrum regulation rulings) are placed onuse of the shared spectrum by secondary users. By way of example, onepossible restriction is to limit the secondary use of a spectrum tousage only within authorized (indoor) facilities and to prohibitout-of-door usage by the secondary services. Another possiblerestriction is to implement exclusion zones, which are regionssurrounding AMT sites that are defined to ensure separation distancebetween MBAN systems and AMT receivers. In order to avoid interferenceto an AMT receiver, MBAN operations within part or the entire 2360-2390MHz spectrum are proposed to be prohibited in such exclusion zones, evenif the MBAN operation is limited to a healthcare facility.

To facilitate enhanced usage of MBAN systems at hospitals and othermedical facilities, it has been proposed to allocate the wider 2360-2400MHz band (the “MBAN spectrum”) specifically for MBAN services. In theUnited States, the Federal Communications Commission (FCC) adopted anMBAN notice of proposed rulemaking (NPRM) in June 2009. Considering thewide bandwidth, interference-free and good propagation properties of theMBAN spectrum, it would be advantageous for MBAN applications to use theMBAN spectrum to provide medical-grade connectivity if the MBAN spectrumis allocated for MBAN usage.

However, the proposed allocation of the MBAN spectrum for MBAN usage ison a secondary basis, which means MBAN usage would be required bygovernment regulation to protect all the primary users in the MBANspectrum and to accept possible interference from those primary users.The current primary users in the MBAN spectrum include Amateur Radio(2390-2400 MHz), Aeronautical Mobile Telemetry (AMT) (2360-2395 MHz;note that currently only 2360-2390 MHz is in use by AMT); and RadioAstronomy (2370-2390 MHz).

In order to protect the primary users, especially AMT sites, it has beenproposed in the United States to limit MBAN operations in the 2360-2390MHz band to healthcare facilities only. Under this proposed regulatoryscheme, MBAN devices are only allowed to operate in the 2360-2390 MHzwhen they are located within a healthcare facility—if an MBAN systemmoves outside, it is required under this proposed scheme to switch to anew channel outside the 2360-2390 MHz band. Moreover, exclusion zones,which are regions surrounding AMT sites, are proposed to be defined toensure separation distance between MBAN systems and AMT receivers. Inorder to avoid interference to an AMT receiver, MBAN operations withinpart or the entire 2360-2390 MHz spectrum are proposed to be prohibitedin such exclusion zones, even if the MBAN operation is limited to ahealthcare facility.

Compliance with such a regulatory scheme is expected to be based onmanual operations, and should be strict. However, strict compliance isdifficult to ensure by manual approaches, at least because (1) MBANspectrum usage is not visually perceptible; (2) some MBAN systems aremobile; and (3) the manual compliance is distributed amongst numeroushuman personnel, such as physicians, nurses, hospital staff, and soforth.

In a contemplated manual approach, when an MBAN system is prescribed bya health care professional to monitor a patient in a healthcarefacility, a nurse or other health care staff will manually enable thehub device to use part or the entire 2360-2390 MHz spectrum based on theFCC regulation. Later, if the patient is going to move outside thehealthcare facility, for example, due to discharge from hospital, ahealthcare staff member will manually disable the hub device to use the2360-2390 MHz spectrum. The manually enable/disable operations could beimplemented by manually entering a passcode on the hub device or byconnecting the hub device with a specific device (for example, plug aUSB key on the hub device) and a program running on the hub device orthe specific device could automatically enable/disable the 2360-2390 MHzspectrum access of the hub device.

However, such manual administration method employs substantial staffintervention and significantly reduces workflow efficiency in thehospital. Manual administration also is not flexible, and may fail todeal effectively with mobile AMT sites (for example, a temporalexclusion zone might be defined from time to time to protect mobile AMTsites or vehicles).

The following provides new and improved apparatuses and methods whichovercome the above-referenced problems and others.

In accordance with one disclosed aspect, a medical system comprises amedical body area network (MBAN) system comprising a plurality ofnetwork nodes intercommunicating via short range wireless communication.The MBAN system includes a spectrum control sub-module that selects anoperating channel or frequency for the short range wirelesscommunication based at least in part on an electronic key specifying ausable spectrum for the short range wireless communication.

In accordance with another disclosed aspect, a method comprises:operating a medical body area network (MBAN) system comprising aplurality of network nodes intercommunicating via short range wirelesscommunication at a selected operating channel or frequency; selectingthe operating channel or frequency from a default spectrum; andselecting the operating channel or frequency from an extended spectrumcomprising the default spectrum and an additional spectrum conditionalupon the MBAN system having an electronic key authorizing use of theadditional spectrum.

In accordance with another disclosed aspect, a medical system comprises:a medical body area network (MBAN) system comprising a plurality ofnetwork nodes intercommunicating via short range wireless communication;a primary users database containing information pertaining to usage of arestricted spectrum by primary users wherein the MBAN systems aresecondary users of the restricted spectrum; an electronic key generationengine comprising a digital processing device configured to generate anelectronic key (E-key) indicative of whether the MBAN system is allowedto use the restricted spectrum based on content of the primary usersdatabase; an MBAN application server configured to distribute the E-keyto the MBAN system; wherein the MBAN system includes a spectrum controlsub-module comprising a digital processor configured to select anoperating channel or frequency for the short range wirelesscommunication based at least in part on whether the E-key authorizes theMBAN system to use the restricted spectrum.

One advantage resides in safe co-existence of secondary users andprimary users in a shared spectrum space.

Another advantage resides in more efficient spectrum usage.

Another advantage resides in principled usage of wireless communicationspectrum by primary and secondary users while maintaining the strictcompliance of secondary users respective to access rights of the primaryusers.

Further advantages will be apparent to those of ordinary skill in theart upon reading and understanding the following detailed description.

FIG. 1 diagrammatically illustrates a medical body area network (MBAN)system in the context of a medical environment including a centralfrequency agility sub-system as disclosed herein.

Disclosed herein is an electronic-key (i.e., “E-key”) based spectrum useenforcement approach that entails little or no manual intervention andonly a modest increase in MBAN system complexity as compared with manualadministration approaches. In some embodiments, the E-key enforcementmechanism operates as a hierarchical solution, in which E-key generationis maintained by an assigned MBAN coordinator, E-key distribution ismaintained by an MBAN application server, and E-key enforcement isintegrated in MBAN hub devices (which may, by way of example, comprisean on-body pendant, a bedside monitor, or so forth). The approachprovides effective MBAN spectrum access control that in suitableembodiments provides a single interface to AMT users to simplifycoordination and control AMT confidential information access, andenables flexibility to provide case-by-case exclusion zone definition.

In some embodiments, the E-key generation process leverages a WirelessMedical Telemetry Service (WMTS) database concept, and is maintained byan assigned MBAN coordinator to provide single interface to AMT users.This simplifies MBAN frequency coordination, facilitates confidentialAMT information access control, and ensures that MBAN users cannotaccess AMT information. In a suitable embodiment, the E-key generationcomponents include an AMT database that stores AMT information providedby AMT users, an MBAN database that stores MBAN information from MBANapplication servers, and an E-key generation engine that generates anE-key for each healthcare facility. The generation engine is suitablyembodied by a network server, computer, digital processing device, or soforth. In some such embodiments, AMT users can access MBAN spectrum usestatus, which can be useful for mobile AMT site optimization.

The AMT database contains input received from AMT users. Content of theAMT Database is preferably accessed by E-key generation algorithm butnot by MBAN systems, which provides access control for confidential AMTinformation. Some suitable AMT information that may be included in theAMT database includes: location and contact information for each AMTsite; the frequency range (or, more generally, spectrum in use) by eachAMT site; the AMT deployment type (e.g., fixed or mobile site); the AMTusage time period (for mobile sites); and AMT site receivercharacteristics (e.g. antenna gain, height, and so forth).

The E-key generation engine is responsible for generating an E-key foreach registered healthcare facility based on the parameters from AMT andMBAN databases. The generation engine has flexibility to providecase-by-case optimization, and a quick response to the establishment ofa mobile AMT site. The E-key generation engine may be responsible forexclusion zone determination, insofar as calculation of an exclusionzone is optionally part of E-key generation algorithm. The Exclusionzone determination may be based on simulations and/or fieldmeasurements, or alternatively exclusion zone geographical scope can bepredefined (e.g., the E-key generation engine may receive thegeographical extent of the exclusion zone as an input provided by theAMT users residing within the exclusion zone). The E-key information foreach healthcare facility (an E-key is generated for each healthcarefacility in some suitable embodiments) may include: healthcare facilityidentification (ID); frequency range of available MBAN spectrum; andexpiration time of the E-key.

The MBAN Database contains input received from MBAN application servers(installed in registered healthcare facilities). Content of the MBANDatabase is accessed by the E-key generation engine, and is optionallyalso accessed by AMT users as this information may be useful for mobileAMT site optimization and to monitor MBAN spectrum usage. Some MBANinformation that is suitably contained in the MBAN Database includes:hospital information such as physical address, location, contactinformation, building height, environment (e.g., urban or rural); thenumber of MBANs; and MBAN device information such as equipment type,manufacturer, deployment type (e.g., fixed or mobile); transmission (TX)Power quantified using an Effective Radiated Power (ERP) metric or othersuitable metric; and the issued E-key.

An MBAN application server is responsible for E-key distribution. Asuitable distribution process is as follows: obtain an E-key from theMBAN database; wait for E-key update commands from MBAN database orperiodically retrieve E-key from MBAN database; generate an E-key foreach registered MBAN; and distribute the E-key to registered MBAN hubdevices. The frequency range of available MBAN spectrum in the generatedE-Key is suitably the same as or a subset of the frequency rangeparameter in the E-key from MBAN database. The E-key distribution can beperformed as follows. For MBAN hub devices with backhaul links (that is,links to the hospital network or other relevant communication network),the MBAN application server periodically sends E-key refresh commands torefresh E-keys stored in those hub devices. For MBAN hub devices withoutbackhaul links, manual administration can be used to update the E-key,such as manually inputting the E-key to the hub device or plugging on aspecific device that delivers the E-key to the hub device. An MBANapplication server also has information about current MBAN spectrum usein its healthcare facility.

The hub device of MBAN is responsible for E-key enforcement. Anillustrative embodiment disclosed herein is directed to a regulatoryscheme in which 2390-2400 MHz is available for MBAN use withoutrequirements of coordination, while 2360-2390 MHz is available for MBANuse on a secondary user basis with requirements of coordination toprotect primary AMT users. In this illustrative embodiment, E-keyenforcement operates as follows. By default, an MBAN hub device wouldonly be allowed to initiate an MBAN on a channel within the 2390-2400MHz spectrum and then MBAN sensor devices could join that MBAN. Once ahub device gets a valid E-key, it would be able to access the MBANchannels within the frequency range defined in the E-key. Only the hubdevice can initiate MBAN channel switch operations. If a hub device doesnot get an E-key update command from MBAN application server before itscurrent E-key expires, it will move out the 2360-2390 MHz spectrum anddisable the access to that spectrum. In this approach, an MBAN sensordevice is not allowed to select an MBAN channel, but rather follows itshub device to switch MBAN channels. If the connection to its hub deviceis lost, the MBAN sensor device will keep quiet (no transmissionoperation) until it reestablishes connection with its hub device.

In some suitable embodiments, healthcare facility registration is donevia web-based tools, similar to web-based tools used for WMTSregistration. The healthcare facility provides hospital information andMBAN device information to the MBAN coordinator. The E-key generationalgorithm generates an E-key for the healthcare facility if the use ofthe 2360-2390 MHz spectrum (part or all) is allowed. The MBAN databasestores the hospital and MBAN device information and the generated E-key.The MBAN database accepts the healthcare facility registration. Once theregistration is accepted, the MBAN application server is able to obtainthe granted E-key from the MBANS coordinator. Based on the grantedE-key, the MBAN application can generate an E-key (the same as or asubset of the E-key from MBAN database) for each activated MBAN toenable possible MBAN operations within the 2360-2390 MHz spectrum.

MBAN activation within this E-key enforcement framework is as follows.An MBAN is prescribed by a healthcare professional, and is activated foroperation. During MBAN activation, an E-key is granted to the hubdevice. For MBANs with no backhaul link, manual administration is usedto enter E-key to the hub device and update the MBAN application serverwith the activated MBAN information. On the other hand, if the hub ofthe MBAN can establish a backhaul link then it obtains an E-key from theMBAN application server first and then selects an MBAN channel withinthe specified available MBAN spectrum to start an MBAN. After the E-keyis granted, MBAN sensor devices join the MBAN. Once the MBAN issuccessfully activated, the activated MBAN information is reported toMBAN application server. Thereafter, periodic E-key refresh commands(e.g. beacon signal) from the MBAN application server keep the E-key ofhub device active. If the hub device cannot receive E-Key refreshcommands before its E-key expires, then the access of the 2360-2390 MHzis disabled. Once a hub device receives a valid E-key from MBANapplication server again (that is, after its previously received E-keyexpired), it is allowed to access the specified available spectrumwithin the 2360-2390 MHz again. MBAN sensor devices keep quiet (notransmission) if they lose the MBAN connection to the hub device.

Changes in spectrum usage by AMT sites is also readily accommodated bythe disclosed E-key enforcement approach. AMT sites or AMT spectrumusage may change from time to time. For example, a new mobile AMT sitemay be established, or an AMT may utilize new AMT spectrum space. Insuch cases, the MBAN E-key system responds in a prompt and timelyfashion in order to protect AMT users. A suitable approach is asfollows. AMT users inform the MBAN coordinator of the planned changesand update the AMT database. The AMT database update triggers the E-keygeneration algorithm to verify if the current E-keys are still validbased on the new AMT information. If needed, the E-key generationalgorithm generates a new E-key for affected hospitals and updates MBANdatabase. The MBAN database sends E-key update commands to MBANapplication servers of the affected hospitals. Once an MBAN applicationserver receives an updated E-key, it updates the E-keys of its allactive MBANs by E-key refresh commands. A hub device updates its localavailable MBAN spectrum information once it receives an updated E-keyfrom its MBAN application server. The hub device also checks whether itscurrent MBAN channel is still available. If not, the hub deviceinitiates a channel switch operation to move its MBAN to a new channelwithin the available spectrum. Once the hub device finishes the E-keyupdate operation, it reports the updated MBAN information to MBANapplication server and such information is further reported the MBANcoordinator to update the MBAN Database. The MBAN application servergenerates a warning message to prompt the required manual administrationeffort to update the E-keys for any MBANs without backhaul links.

With reference to FIG. 1, an illustrative embodiment of the disclosedE-key enforcement scheme is described. A medical body area network(MBAN) 10 includes a plurality of network nodes 12, 14. At least one ofthe network nodes 12, 14 serves as a hub device 14. The network nodes 12communicate with the hub device 14 via a short-range wirelesscommunication protocol. The MBAN 10 is also sometimes referred to in therelevant literature by other equivalent terms, such as a body areanetwork (BAN), a body sensor network (BSN), a personal area network(PAN), a mobile ad hoc network (MANET), or so forth—the term medicalbody area network (MBAN) 10 is to be understood as encompassing thesevarious alternative terms.

The illustrative MBAN 10 includes four illustrative network nodes 12, 14including the hub device 14; however, the number of network nodes can beone, two, three, four, five, six, or more, and moreover the number ofnetwork nodes may in some embodiments increase or decrease in an ad hocfashion as sensor nodes are added or removed from the network to add orremove medical monitoring capability. The network nodes 12 are typicallysensor nodes that acquire physiological parameters such as heart rate,respiration rate, electrocardiographic (ECG) data, or so forth; however,it is also contemplated for one or more of the network nodes to performother functions such as controlled delivery of a therapeutic drug via askin patch or intravenous connection, performing cardiac pacemakingfunctionality, or so forth. A single network node may perform one ormore functions. The illustrative network nodes 12 are disposed on theexterior of an associated patient P; however, more generally the networknodes may be disposed on the patient, or in the patient (for example, anetwork node may take the form of an implanted device), or proximate tothe patient within the communication range of the short-rangecommunication protocol (for example, a network node may take the form ofa device mounted on an intravenous infusion pump (not shown) mounted ona pole that is kept near the patient, and in this case the monitoredpatient data may include information such as the intravenous fluid flowrate). It is sometimes desirable for the network nodes to be made assmall as practicable to promote patient comfort, and to be of lowcomplexity to enhance reliability—accordingly, such network nodes 12 aretypically low-power devices (to keep the battery or other electricalpower supply small) and may have limited on-board data storage or databuffering. As a consequence, the network nodes 12 should be incontinuous or nearly continuous short-range wireless communication withthe hub device 14 in order to expeditiously convey acquired patient datato the hub device 14 without overflowing the data buffer.

The hub device 14 (also sometimes referred to in the relevant literatureby other equivalent terms, such as “gateway device” or “hub node”)coordinates operation of the MBAN 10 by collecting (via the Zigbee,Bluetooth™, or other short-range wireless communication protocol)patient data acquired by the sensors of the network nodes 12 andtransmitting the collected data away from the MBAN 10 via a longer rangecommunication protocol. The short-range wireless communication protocolpreferably has a relatively short operational range of a few tens ofmeters, a few meters, or less, and in some embodiments suitably employsan IEEE 802.15.4 (Zigbee) short-range wireless communication protocol ora variant thereof, or a Bluetooth™ short-range wireless communicationprotocol or a variant thereof. Both Bluetooth™ and Zigbee operate in afrequency spectrum of around 2.4-2.5 GHz. Although Bluetooth™ and Zigbeeare suitable embodiments for the short-range wireless communication,other short-range communication protocols, including proprietarycommunication protocols, are also contemplated. Moreover, theshort-range wireless communication can operate at other frequenciesbesides the 2.4-2.5 GHz range, such as ranges in the hundreds ofmegahertz, gigahertz, tens-of-gigahertz, or other ranges. Theshort-range communication protocol should have a sufficient range forthe hub device 14 to communicate reliably with all network nodes 12 ofthe MBAN system 10. In FIG. 1, this short-range wireless communicationrange is diagrammatically indicated by the dotted oval used to delineatethe MBAN system 10. The short-range wireless communication is typicallytwo-way, so that the network nodes 12 can communicate information (e.g.,patient data, network node status, or so forth) to the hub device 14;and the hub device 14 can communicate information (e.g., commands,control data in the case of a therapeutic network node, or so forth) tothe network nodes 12. The illustrative hub device 14 is a wrist-mounteddevice; however, the hub device can be otherwise mounted to the patient,for example as a necklace device, adhesively glued device, cellulartelephone, or so forth. It is also contemplated for the hub device to bemounted elsewhere proximate to the patent, such as being integrated withan intravenous infusion pump (not shown) mounted on a pole that is keptnear the patient, or as a set-top box.

The hub device 14 also includes a transceiver (not shown) providing thelonger-range communication capability to communicate data off the MBANsystem 10. In the illustrative example of FIG. 1, the hub device 14wirelessly communicates with an access point (AP) 20 of a hospitalnetwork 22. The illustrative AP 20 is a wireless access point thatcommunicates wirelessly with the hub device 14. In the illustrativeembodiment the hospital network 22 also includes additional accesspoints, such as illustrative access points AP 23 and AP 24, that aredistributed throughout the hospital or other medical facility. Toprovide further illustration, a nurses' station 26 is diagrammaticallyindicated, which is in wireless communication with the AP 24 andincludes a display monitor 28 that may, for example, be used to displaymedical data for the patient P that are acquired by the MBAN system 10and communicated to the nurses' station 26 via the path comprising theAP 20, the hospital network 22, and the AP 24. By way of anotherillustrative example, the hospital network 22 may provide access with anelectronic patient records sub-system 30 in which is stored medical datafor the patient P that are acquired by the MBAN system 10 andcommunicated to the electronic patient records sub-system 30 via thepath comprising the AP 20 and the hospital network 22. The illustrativelonger-range communication between the hub device 14 and the AP 20 iswireless, as diagrammatically indicated in FIG. 1 by a dashed connectingline. (Similarly, wireless communication between the AP 24 and thenurses' station 26 is indicated by a dashed connecting line). In somesuitable embodiments, the longer-range wireless communication issuitably a WiFi communication link conforming with an IEEE 802.11wireless communication protocol or a variant thereof. However, otherwireless communication protocols can be used for the longer-rangecommunication, such as another type of wireless medical telemetry system(WMTS). Moreover, the longer range communication can be a wiredcommunication such as a wired Ethernet link (in which case the hubdevice includes at least one cable providing the wired longer rangecommunication link).

The longer range communication is longer range as compared with theshort-range communication between the network nodes 12 and the hubdevice 14. For example, while the short-range communication range may beof order a few tens of centimeters, a few meters, or at most perhaps afew tens of meters, the longer range communication typically encompassesa substantial portion of the hospital or other medical facility throughthe use of multiple access points 20, 23, 24 or, equivalently, multipleEthernet jacks distributed throughout the hospital, in the case of awired longer-range communication. Elsewhere in this application, thelonger range communication 20, 22, 23, 24 is referred to as a backhaullink.

The longer-range communication, if wireless, requires more power thanthe short-range communication—accordingly, the hub device 14 includes abattery or other power source sufficient to operate the longer-rangecommunication transceiver. Alternatively, the hub device 14 may includea wired electrical power connection. The hub device 14 also typicallyincludes sufficient on-board storage so that it can buffer a substantialamount of patient data in the event that communication with the AP 20 isinterrupted for some time interval. In the illustrative case of wirelesslonger-range communication, it is also to be understood that if thepatient P moves out of range of the AP 20 and into range of another AP(for example, AP 23 or AP 24) then the IEEE 802.11 or other wirelesscommunication protocol employed by the hospital network 22 (includingits wireless access points 20, 23, 24) provides for the wireless link toshift from AP 20 to the newly proximate AP. In this regard, although thepatient P is illustrated as lying in a bed B, more generally it iscontemplated for the patient P to be ambulatory and to variously moveinto and out of range of the various access points 20, 23, 24. As thepatient P thus moves, the MBAN 10 including the network nodes 12 and thehub device 14 moves together with the patient P.

In the MBAN 10, the network nodes 12 communicate with the hub device 14via the short-range wireless communication. However, it is alsocontemplated for various pairs or groups of the network nodes 12 to alsointercommunicate directly (that is, without using the hub device 14 asan intermediary) via the short-range wireless communication. This may beuseful, for example, to coordinate the activities of two or more networknodes in time. Moreover, the hub device 14 may provide additionalfunctionality—for example, the hub device 14 may also be a network nodethat includes one or more sensors for measuring physiologicalparameters. Still further, while the single hub device 14 isillustrated, it is contemplated for the coordinating functionality (e.g.data collection from the network nodes 12 and offloading of thecollected data via the longer range wireless communication) to beembodied by two or more network nodes that cooperatively perform thecoordinating tasks.

In illustrative FIG. 1, only the single MBAN system 10 is illustrated indetail. However, it will be appreciated that more generally the hospitalor other medical facility includes a plurality of patients, each havinghis or her own MBAN system. This is diagrammatically shown in FIG. 1 bytwo additional MBAN systems 35, 36 also communicating with the AP 20 viathe longer range wireless communication. More generally, the number ofMBAN systems may be, by way of some illustrative examples: two, three,four, five, ten, twenty, or more. Indeed, it is even contemplated for asingle patient to have two or more different, independently operatingMBAN systems (not illustrated).

With continuing reference to FIG. 1, an MBAN application server 40communicates with the MBAN systems 10, 35, 36 via the longer rangecommunication or backhaul link 20, 22, 23, 24 to perform variousapplication tasks. By way of illustrative example, the MBAN applicationserver 40 may perform tasks such as coordinating data transfer from thehub device 14 to the electronic patient records sub-system 30 forstorage, coordinating data transfer from the hub device 14 to thedisplay monitor 28 for display, and so forth. Toward this end, the MBANapplication server 40 maintains an MBAN database 42 containing relevantinformation about each active MBAN system 10, 35, 36.

To provide spectrum usage control, the MBAN application server 40further includes or has access to an electronic key (E-key) generationengine 44. The E-key generation device generates an electronic key(E-key) that specifies what spectrum is available for MBAN usage.Various limitations can exist on the available spectrum, such aslimitations imposed by primary users where MBAN communications are asecondary usage; limitations on spectrum based on region, nationalcountry, or other geographic locale; or so forth. The limitations onavailable spectrum may vary as a function of time, and such variationmay be periodic or aperiodic.

The E-key generation engine 44 is suitably embodied by a computer,network server, or other digital processing device. The MBAN applicationserver 44 is also suitably embodied by a computer, network server, orother digital processing device, which may be the same as or differentfrom the digital processing device embodying the E-key generation engine44. In some embodiments the E-key generation engine 44 is embodied as anapplication program executing on the MBAN application server 40.

By way of illustrative example, in the illustrative embodiment the2360-2400 MHz spectrum is referred to in this illustrative example asthe “MBAN spectrum”. However, the portion from 2360-2390 MHz isallocated for MBAN usage on a secondary basis, with aeronautical mobiletelemetry (AMT) users being the primary users for the 2360-2390 MHzspectrum. In the illustrative example, the limitations on MBAN usage inthe 2360-2390 MHz spectrum space is implemented by regulationsincluding: (1) limiting MBAN usage in this spectrum space to MBANsystems operating indoors in designated medical facilities and (2)defining stationary “exclusion zones” around AMT sites—no MBAN usage ofthe portion of the 2360-2390 MHz band that is currently in use by AMTusers is allowed at any time in any such stationary exclusion zone; and(3) defining temporary exclusion zones corresponding to mobile orintermittent AMT use—no MBAN usage of the portion of the 2360-2390 MHzband that is currently in use by AMT users is allowed in such atemporary exclusion zone during the time it is in place. A consequenceof (3) is that usage of part or all of the 2360-2390 MHz spectrum spacein a designated medical facility may be temporarily barred during thetime when a temporary exclusion zone encompassing the medical facilityis in place.

The foregoing example is merely illustrative—in general, limitations maybe placed on various spectrum spaces at various times and variouslocations as dictated by governing regulations promulgated by relevantgovernment regulatory agencies, hospital policies, or so forth.

To implement spectrum limitations, the E-key generation engine 44receives information on spectrum limitations. In the illustrativeexample, the spectrum limitations are imposed by AMT users, andaccordingly the spectrum limitations (or information from which spectrumlimitations can be determined) are provided to the E-key generationengine 44 in the form of a primary users (e.g., AMT) database 46. Foreach AMT site, some information suitably contained in the AMT Database46 includes: site location; contact information for the AMT site;frequency range (that is, spectrum in use) by the AMT site; AMTdeployment type (that is, fixed or mobile site), usage time period(relevant for a mobile site); and site receiver characteristics (e.g.antenna gain, height, or so forth). In some embodiments, the content ofthe AMT database 46 is accessible only by the E-key generation engine44, but not by other persons or entities having access to the hospitalnetwork 22 or the MBAN application server 40. Such access limitationprovides access control and security for confidential AMT information.

Additionally, the E-key generation engine 44 obtains information aboutthe medical facility and/or the MBAN systems. In a suitable embodiment,the information is stored in the MBAN database 42 and is accessible bythe E-key generation engine 44 either directly or via the MBANapplication server 40. Some medical facility-related informationsuitably contained in the MBAN Database 42 includes: hospitalinformation such as physical address, location, contact information;building height (which may be relevant for estimating the range of radiofrequency interference due to MBAN operation); environment (e.g., urbanor rural); number of currently active MBAN systems; number of MBANsystems authorized for concurrent operation, or so forth. The MBANdatabase 42 also suitably stores information about each MBAN system,such as: equipment type; manufacturer; deployment type (e.g., fixed ormobile); transmission (TX) Power, for example measured by an effectiveradiated power (ERP) metric; and the E-key (if any) issued to each MBANsystem.

Based on the content of the AMT database 46 and the MBAN database 42,the E-key generation engine 44 determines exclusion zones (bothstationary and mobile) and hence determines whether the hospital orother medical facility is located within an exclusion zone (ordetermines when the hospital or other medical facility is or will belocated within an exclusion zone, in the case of a mobile or temporaryexclusion zone). The geographical extent of an exclusion zone can becalculated based on electromagnetic simulation (or an approximationthereof, such as a assuming a circular exclusion zone centered on theAMT site and having a specified radius), field measurements, or acombination thereof. Alternatively, the geographical extent of theexclusion zone can be pre-calculated information that is stored in theAMT database 46. Based on this information, the E-key generation engine44 generates an electronic key (E-key) indicative of the spectrum spaceusable for MBAN systems at the hospital or other medical facility.

In an alternative approach, the AMT user can determine which portion (ifany) of the shared spectrum is to be usable by MBAN systems of thehospital or other medical facility, and the AMT database 46 can thenstore this spectrum information for retrieval by the E-key generationengine 44.

The E-key generated by the E-key generation engine 44 is suitablydistributed to the various MBAN systems 10, 35, 36 by the MBANapplication server 40 via the longer range communication or backhaullink 20, 22, 23, 24, and a copy of the E-key 50 is stored at the hubdevice 14 of each MBAN system 10. Optionally, the MBAN applicationserver 40 stores information about the E-key assigned to each MBANsystem 10, 35, 36. If the MBAN is not connected with a backhaul, thenthe E-key can be loaded manually, or using a portable USB drive, or soforth.

In some embodiments, different E-keys can be assigned to different MBANsystems within the same medical facility. For example, larger MBANsystems or MBAN systems including network nodes having strongertransmitters may be assigned a more restrictive E-key (or no E-key atall) since the larger and/or stronger-transmitting MBAN system may bemore likely to interfere with a neighboring AMT site. Different E-keysmay also be assigned to different MBAN systems based on their locationwithin the medical facility. For example, a more restrictive E-key (orno E-key at all) may be assigned to MBAN systems located at elevatedpositions where they are more likely to produce problematic interferencefor AMT sites.

At the MBAN system, a spectrum control sub-module 52 of the hub device14 (suitably embodied by software or firmware running on a digitalprocessor of the hub device 14) assigns a channel or frequency for theshort-range communication of the MBAN system 10. In one suitableapproach, the spectrum control sub-module 52 of the hub device 14assigns a channel or frequency in a default spectrum space (e.g.,2390-2400 MHz in the illustrative example), and only assigns a channelor frequency in the shared or otherwise restricted spectrum space (e.g.,2360-2390 MHz in the illustrative example) if the E-key 50 authorizesusage of this restricted spectrum space. In this way, the defaultoperation does not impinge on any restricted spectrum, and theadditional restricted spectrum is only utilized (or considered forutilization) if the E-key 50 affirmatively authorizes usage of theadditional restricted spectrum.

The generated E-key can take various forms. In one suitable approach,the E-key is a single binary value, for which one binary value (e.g.,“1”) indicates the spectrum space 2360-2390 MHz is available for MBANuse and the other binary value (e.g., “0”) indicates the spectrum space2360-2390 MHz is not available for MBAN use. Alternatively, the E-keycan specify the spectrum space using any suitable encoding. This may beappropriate in embodiments for which different portions of the spectrummay be variously available or unavailable for MBAN use, such that asingle binary value is insufficient to convey the MBAN-usable spectrum.

Optionally, the E-key also includes an expiration time, which may bespecified either in absolute time (i.e., a date certain on which theE-key expires) or in relative time (e.g., the E-key is valid for 24hours, or 10 minutes, et cetera from the time of receipt at the MBAN).Specifying an expiration time advantageously ensures that an MBAN systemwill not use shared or otherwise restricted spectrum authorized by theE-key indefinitely (for example, after the patient wearing the MBANsystem is discharged from the hospital).

Optionally, the E-key also includes a healthcare facilityidentification. In such embodiments, the E-key authorizes use of theshared or otherwise restricted spectrum within the identified healthcarefacility. It is contemplated in such embodiments for a single MBANsystem to have two or more E-keys for two or more corresponding medicalfacilities, so that different usable spectrums may be specified for thedifferent facilities by the different E-keys. This may be useful, forexample, if the patient transfers between different medical facilitiesfor different treatments. In a suitable operating approach, the MBANsystem determines in which facility it is currently located (and, hence,which E-key to use) based on which backhaul link with which it canconnect.

In embodiments in which the E-key 50 has an expiration time, thatexpiration time can be selected to provide various functionality. Forexample, in some embodiments in which the longer range communication orbackhaul link 20, 22, 23, 24, is robust and reliable and fast, theexpiration time may be set to be short, e.g. of order a few minutes, ora few seconds, or less. In such embodiments, the expiration timeadvantageously ensures that a mobile MBAN system quickly (i.e., within afew minutes, or a few seconds, or less) vacates the restricted spectrumas soon as the MBAN system moves outside of range of the longer rangecommunication or backhaul link 20, 22, 23, 24 (for example, because thepatient leaves the medical facility).

In other embodiments the expiration time is longer, which reducestransmission load on the longer range communication or backhaul link 20,22, 23, 24. In such embodiments other mechanisms can be employed tolimit spectrum usage when the patient leaves the medical facility. Forexample, the MBAN system can switch to an unrestricted frequency orchannel (e.g., in the 2390-2400 MHz range in the illustrative example)if the signal from the longer range communication or backhaul link 20,22, 23, 24 is lost or becomes weak (thus possibly indicating that theMBAN system is moving away from the medical facility). In the case ofcontrolled movement, such as patient discharge or patient transportationoutside the hospital for an off-site medical procedure, the E-key may beinvalidated automatically by the MBAN application server 40 (in cases inwhich the hub device has an operative backhaul link) or the E-key may beinvalidated manually (in cases in which the hub device does not have anoperative backhaul link).

One circumstance that can arise is that a given patient with an active(and mobile) MBAN may move outside of the hospital. This is of concernif the regulatory scheme only allows MBAN devices to operate in therestricted band (e.g., 2360-2390 MHz in the illustrative example) whenthey are located within a healthcare facility. Under such a regulatoryscheme, if an MBAN system moves outside, it is required to switch to anew channel outside the restricted band (e.g., to the band 2390-2400 MHzin the illustrative example). If the expiration time of the E-key isonly a few minutes, or a few seconds, or less, then this may besufficient protection against uncontrolled patient movement. In suchembodiments with fast E-key expiration, if the patient moves outside theservice area of the hospital network 22, then the hub device will not beable to get E-key refresh commands from MBAN application server 40 andso once the E-key expires (i.e., in a few minutes, or a few seconds, orless), use of the 2360-2390 MHz spectrum is automatically disabled.

As another approach, if the patient only has sensor devices on-body, sothat the hub device does not move outside with the patient, then theMBAN sensor devices would not be able to hear the hub device, then theywould keep quiet.

As yet another approach, a radio frequency identification (RFID) tag 60(shown diagrammatically in enlargement in diagrammatic FIG. 1, butsuitably, by way of example, mounted on or in the hub device 14)disposed on the patient, on or in the hub device 14, or otherwiseproximate to the (mobile) MBAN can be used in conjunction with RFIDreaders at doors of the medical facility to detect when the patient Penters or leaves the medical facility.

If a network node 12 (other than the hub node 14) that is currentlyoperating at a restricted channel or frequency loses communication withthe hub node 14 then the network node suitably stops communicating so asto ensure that it does not generate interference for primary users.Communication can be reestablished by the hub device 14, oralternatively the network node 12 can attempt to reestablishcommunication with the hub device 14 using an unrestricted frequency orchannel (e.g., in the range 2390-2400 MHz in the illustrative example).

This application has described one or more preferred embodiments.Modifications and alterations may occur to others upon reading andunderstanding the preceding detailed description. It is intended thatthe application be construed as including all such modifications andalterations insofar as they come within the scope of the appended claimsor the equivalents thereof.

Having thus described the preferred embodiments, the invention is nowclaimed to be:
 1. A medical system comprising: a medical body areanetwork (MBAN) system comprising a plurality of network nodesintercommunicating via short-range wireless communication, the MBANsystem including a spectrum control sub-module comprising a digitalprocessor configured to select an operating channel or frequency for theshort-range wireless communication based at least in part on anelectronic key specifying a usable spectrum for the short-range wirelesscommunication.
 2. The medical system of claim 1, wherein the spectrumcontrol sub-module selects an operating channel or frequency from aspectrum comprising a combination of (1) a default spectrum and (2) arestricted spectrum authorized for use by the MBAN system by theelectronic key.
 3. The medical system of claim 1, wherein the electronickey comprises a first electronic key associated with a first medicalfacility and a second electronic key associated with a second medicalfacility, and the spectrum control sub-module selects an operatingchannel or frequency for the short-range wireless communication based atleast in part on one of the first and second electronic keys selectedbased on a determined location of the MBAN system.
 4. A medical systemcomprising: a medical body area network (MBAN) system comprising aplurality of network nodes intercommunicating via short-range wirelesscommunication, the MBAN system including a spectrum control sub-modulecomprising a digital processor configured to select an operating channelor frequency for the short-range wireless communication based at leastin part on an electronic key specifying a usable spectrum for theshort-range wireless communication; wherein the spectrum controlsub-module selects an operating channel or frequency from a spectrumcomprising a combination of (1) a default spectrum and (2) a restrictedspectrum authorized for use by the MBAN system by the electronic key;and wherein the electronic key includes an expiration time and thespectrum control sub-module selects an operating channel or frequencyfrom a spectrum comprising: a combination of (1) a default spectrum and(2) a restricted spectrum authorized for use by the MBAN system by theelectronic key conditional upon the electronic key not having expiredbased on the expiration time; and only the default spectrum conditionalupon the electronic key having expired based on the expiration time. 5.The medical system of claim 1, further comprising: a longer rangecommunication or backhaul link via which the MBAN system receives theelectronic key.
 6. The medical system of claim 5, wherein the MBANsystem includes a plurality of network nodes communicating with a hubdevice via short-range wireless communication, the hub device alsocommunicating via the longer range communication or backhaul link, thehub device embodying the spectrum control sub-module.
 7. The medicalsystem of claim 5, wherein the spectrum control sub-module selects anoperating channel or frequency from a spectrum comprising: a combinationof (1) a default spectrum and (2) a restricted spectrum authorized foruse by the MBAN system by the electronic key conditional uponcommunication of the MBAN system with the longer range communication orbackhaul link satisfying a strength of communication criterion; and onlythe default spectrum conditional upon communication of the MBAN systemwith the longer range communication or backhaul link not satisfying thestrength of communication criterion.
 8. The medical system of claim 7,wherein the strength of communication criterion is satisfied if the MBANsystem is communicating with the longer range communication or backhaullink and is not satisfied if the MBAN system is not communicating withthe longer range communication or backhaul link.
 9. The medical systemof claim 7, wherein the strength of communication criterion is satisfiedif a signal strength of the longer range communication or backhaul linkat the MBAN system exceeds a threshold level.
 10. A method comprising:operating a medical body area network (MBAN) system comprising aplurality of network nodes intercommunicating via short-range wirelesscommunication at a selected operating channel or frequency; selectingthe operating channel or frequency from a default spectrum; andselecting the operating channel or frequency from an extended spectrumcomprising the default spectrum and an additional spectrum conditionalupon the MBAN system having an electronic key authorizing use of theadditional spectrum.
 11. The method of claim 10, further comprising:reverting to selecting the operating channel or frequency from thedefault spectrum conditional upon a time-based expiration of theelectronic key.
 12. The method of claim 10, further comprising:reverting to selecting the operating channel or frequency from thedefault spectrum conditional upon receiving an indication that the MBANsystem is outside of a medical facility with which the electronic key isassociated.
 13. The method of claim 12, further comprising: selectingthe operating channel or frequency from a second extended spectrumcomprising the default spectrum and a second additional spectrumconditional upon (i) the MBAN system having a second electronic keyauthorizing use of the second additional spectrum and (ii) an indicationthat the MBAN system is inside of a second medical facility with whichthe second electronic key is associated.
 14. The method of claim 10,further comprising: generating the electronic key based on informationabout primary usage of the additional spectrum.
 15. The method of claim10, further comprising: generating the electronic key to allow usage ofthe additional spectrum based on information that there is no primaryuser occupying the additional spectrum.
 16. The method of claim 14,wherein the information about primary usage or the information thatthere is no primary user occupying the additional spectrum is based onsite location information about one or more sites of primary users. 17.One or more non-transitory digital storage media storing instructionsexecutable by a digital processor to perform a method as set forth inclaim 10.